Sanmen 2 completes hydrostatic testing

05 September 2017

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The second AP1000 unit under construction at the Sanmen site in China's Zhejiang province has completed cold hydrostatic testing of its primary circuit. The tests are an important step in the commissioning of new units.

Sanmen units 1 and 2 (Image: SNPTC)

Cold hydrostatic testing involves filling the reactor's primary circuit with water, which is circulated at high pressure by the reactor coolant pumps to verify that the welds, joints, pipes and components of the reactor coolant system and associated high-pressure systems meet regulatory standards. The coolant pumps will help to maintain the reactor's internal temperature at a safe level during operations.

State Nuclear Power Technology Company (SNPTC) announced yesterday that cold hydrostatic testing began at 0.59am on 2 September. The pressure within the circuit was gradually raised to a maximum of 21.6 MPa and held at that level for 10 minutes. At 10.15am, the pressure was reduced to 17.5 MPa while all the welds and mechanical connections were checked. The tests were completed at 2.00pm the same day.

Similar tests were completed at unit 1 of the Sanmen plant in May 2016, while those at unit 1 of the Haiyang plant in Shandong province were completed in July 2016.

Sanmen 1 is expected to be the first Westinghouse AP1000 to begin operating later this year, while Haiyang 1 is also expected to begin operating by the end of the year. Sanmen 2 and Haiyang 2 are expected to start up in 2018.

Four AP1000 reactors were also being built in the USA - two each at Vogtle and Summer. However, construction of the two Summer units was suspended last month.